[Coral-List] Newly discovered reef

[Eugene Shinn]

Thank you Alina for setting the record straight as you often do. There 
are few of us old timers left as new profs and students begin 
rediscovering coral reefs. I wonder who still maintains a reprint 
collection of the older papers? My collection was extensive but just 
before COVID struck I changed offices and was encouraged to discard my 
older reprints. They would not fit in my new smaller office. I dumped 25 
file drawers (nearly a ton of precious reprints.)

Yes, that article about the “newly discovered coral reef” made the 
papershere as well as elsewhere. Yes Alina, it has to be a guyot. If not 
a guyot then a piece of the Great Barrier reef. How many young reef 
worker know that even the Great Barrier Reef consists of a thin skin of 
Holocene buildup over a Tertiary substrate. The thickest coral buildups 
(up to around 300 ft thick) are patch reefs growing in the deep lagoon 
behind the Great Barrier Reef.The barrier it self, like our Florida Keys 
reefs are composed of thin coral build ups.

I began spearfishing on the Florida reefs as a teenager in the early 
1950s. Everything looked like a coral reef to me. However, in recent 
years after doing extensive coring and seismic surveys with the USGS we 
discovered vast stretches of the so-called Florida Keys reefs are 
actually exposed Pleistocene coral buildups that formed 125,000 years 
ago. They were then exposed by a huge drop in sea level until between 
6,000 and 7,000 when Holocene sea level world-wide began rising over the 
dead reefs. Only in those places (mainly named reefs with lighthouses) 
growing over previous topographic highs(created by Pleistocene coral) 
did Holocene reefs grow thicker (up to 30 -40 ft. thick) And even in 
those reefs, for example Molasses Reef which is one of the most famous 
coral reefs in the Keys, the thin layer of sand in the groves between 
the Holocene coral spurs directly overlies Pleistocene coral. Similar to 
the Australian coral reef, the thickest reefs in the Keys consist of 
patches in the lagoon area behind the linear outer reefs that have spurs 
and grooves on their seaward sides. Of course our lagoon areas behind 
the outer reef chain are no where near the depths found behind the 
Australian Barrier Reef.

Some years ago I did a mission in the Aquarius underwater habitat which 
is situated seaward of the main outer reef line and lies in 50-55 ft of 
water. With support from divers lowering equipment from the surface, 
Jack Kindinger and I core drilled down through 49 feet of coral. What 
did we find? Roughly 6 inches of Holocene (mainly a crust of laminated 
red brown caliche. (Caliche forms on dry land) The remainder of the 49 
ft core consisted of Pleistocene head corals. We had expected to find 
/Acropora palmata/ but found none. This remains a mystery to be solved. 
In all cases our cores showed the outer Florida reef tract is underlain 
by Pleistocene head corals like that supporting the underwater habitat.

In more recent years Toth, et al. (2018) at the USGS St Petersburg 
office carbon dated our USGS collection of coral cores and determined 
that the outer Florida coral reefshutdown 3,000 years ago.

I am reminded of this every time I read a new article about efforts to 
transplant corals to our now mostly dead coral reefs. That the main 
builders are no longer building coral reefs does not mean they are no 
long prime dive sites. There are still sponges, sea whips, fans, 
coraline algae, etc., and beautiful schools of fish and many 
invertebrates. Go diving with tourists and listen to what they talk 
about. It’s the Fish! The key element is clear Gulfstream water that 
allows tourist divers to observe these colorful wonders. Although 
transplanting may be futile, especially in our life-time, the research 
involved is causing coral scientists to learn more about the secretes of 
what corals require to remain alive. Hopefully we will learn why corals 
began dying 3,000 years ago. Gene

-- 
No Rocks, No Water, No Ecosystem (EAS)
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E. A. Shinn, Courtesy Professor
University of South Florida
College of Marine Science Room 221A
140 Seventh Avenue South
St. Petersburg, FL 33701
<eugeneshinn at mail.usf.edu>
Tel 727 553-1158
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